The present invention relates to a ferroelectric liquid crystal display.
Recently, ferroelectric liquid crystal materials have attracted interests of researchers in the display fields since there is possibility by use of this kind of liquid crystal materials to realize non-volatile and low-power-consumption displays. Briefly described, a liquid crystal device of this kind is composed of a ferroelectric liquid crystal layer sandwiched between and supported by a pair of polarizing plates whose polarization plates are aligned normal to each other. The display operation is based on the birefringence of the liquid crystal material of this kind. The liquid crystal layer has different refractive indices in perpendicular directions parallel to which the polarizing plates are respectively aligned. The contrast ratio and the color tone of the display of this kind depend mainly upon the retardation thereof. The retardation is defined as the product of the thickness of the liquid crystal layer and the differential refractive index between the different indices.
The retardation corresponds to the rotation of the polarization plane of light passing through the liquid crystal layer. The differential refractive indices of ferroelectric liquid crystal materials are limited to a range of about from 0.12 to 0.20 in order to maintain other characteristics such as spontaneous polarizations, viscosity coefficients, transition temperatures and so on. In this case, the thickness of the liquid crystal material must be as small as one micrometer in order to avoid chromatic aberration. Otherwise, the image constructed by the display become unsightly because of undesirable yellowish colors. In order to form a liquid crystal layer having such a small thickness of this order, two substrates have to be located so close to each other to constitute a space of one micrometer thickness. This severe configuration substantially increases the likelihood of formation for short current paths therebetween, and therefore decreases the yield.